The following description relates to the communication of characterization data between electrically connected components.
Fuel metering units (FMU) have inherent deviation from desired flow schedules as a result of accuracy limitations in variable differential transformer (VDT) demodulation, pressure droop, friction, fluid leakages and other influences. Various schemes have been invented to counter these effects and improve overall accuracy, but since these schemes usually only address a particular effect there is a limitation to their overall effectiveness.
Previous techniques used to transfer such data have been implemented as memory devices or personality modules in the FMU that are interrogated over a communications bus by a full authority digital engine controller (FADEC). Such solutions require sophisticated electronic circuit assemblies that are capable of surviving in harsh engine environments yet still are able to perform the necessary communications. FADECs are also often limited in the input/output resources needed to communicate with such sophisticated memory devices or personality modules. Some such solutions also add to the cost and complexity of the wiring between the FADEC and the FMU to enable communications between such solutions and the FADEC. These factors can severely reduce how much coded information can be made available to the FADEC, and as a result can reduce the usefulness of a FMU characterization correction scheme.